IDE stopped responding due to a never-ending wait() called from CloneableEditorInitializer.waitForFinishedInitialization().
I think I got to the state after an attempt to navigate to a Java class/method using Ctlr-click (but I am not sure).
See the attached thread-dump for more information.
(Thread-dump was generated using JVisualVM.)
--
NetBeans 7.4
Java version "1.7.0_45"
Java(TM) SE Runtime Environment (build 1.7.0_45-b18)
Java HotSpot(TM) 64-Bit Server VM (build 24.45-b08, mixed mode)
Windows 7 64-bit